One avenue for minimizing the size and enhancing protection, quality and reliability of an electronic product is to reduce the substrate outline of a printed circuit board (PCB) and increase the design robustness, margins and interconnect schemes integrity of the electronic product. Radio batteries used in the portable radio communications field often require numerous components to support charging and radio interface operations. Therefore, a reduced PCB in a radio battery with enhanced protection, quality and reliability, for example, must still be capable of housing all required circuitry for the radio battery. Consider an example where in a battery product used in portable radios approximately 80 components need to be housed on the PCB, including 4 connection tabs for connections with a battery charger contacts, 3 connection tabs for connections with a radio contacts, and 3 connection tabs for connections with a battery cell contacts, assuming a 2 Li ion cells in series, 1 cell in parallel cell pack configuration. In order to connect the PCB with all of the required contacts, the connection tabs on the PCB are typically spot welded to the appropriate contacts using spot welding or resistance welding. When the tabs are spot welded to the contacts, 1 connection tab typically requires a space of 84 mm2 on one side (referred to as a first side) of the PCB.
In addition, to the space required on the first side of the PCB for each connection tab, an area on the opposite side of the PCB needs to be reserved (this area is also referred to herein as a keep-out area) to support the spot welding, ensure the rigidity, and maintain a best practice pull/peel force of 6 lb minimum for the weld. The reserved space in totality also accounts for errors associated with placement and reflow of the surface base tabs as well as the misalignment and overhanging of tabs by human and/or machinery including, for example, alignment fixtures, tools and Surface Mount Technology (SMT) reflow ovens. Therefore, for a battery product with 10 connection tabs, a space of 840 mm2 must be reserved on the first side of the PCB to allow for the clearances to counter and cater for the aforementioned drawbacks. If a reduced PCB in the battery product provides 1496 mm2 on one side, then the tabs will use up 56% of the available space on the first side. While the remaining space on the first side of the PCB may be reserved for test point and traces, the space on the opposite side of the reduced PCB is not large enough to house the remaining 70 components of the battery product. In order to fit all the components and route all the traces on the PCB, the battery product may require a 4-6 layer board. However, using a multilayer PCB increases the cost of the product. Moreover, real estate for components placement would be still wanting, thus it would be eminent to increase the PCB size dimensions.
Accordingly, there is a need for an apparatus and method for miniaturizing the size of a printed circuit board while still accommodating the product components, coupled with improvements with regards to protection due to fault modes, quality, and reliability.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.